A Positive Feedback Onto ENSO Due to Tropical Instability Wave (TIW)‐Induced Chlorophyll Effects in the Pacific

2019 ◽  
Vol 46 (2) ◽  
pp. 889-897
Author(s):  
Feng Tian ◽  
Rong‐Hua Zhang ◽  
Xiujun Wang
Keyword(s):  
Positive Feedback ◽  
Instability Wave ◽  
The Pacific

scholarly journals Near-Surface Shear Flow in the Tropical Pacific Cold Tongue Front*

2009 ◽  
Vol 39 (5) ◽  
pp. 1200-1215 ◽  
Author(s):  
Meghan F. Cronin ◽  
William S. Kessler
Keyword(s):  
Turbulent Viscosity ◽  
Instability Wave ◽  
Surface Currents ◽  
Cold Tongue ◽  
Surface Shear ◽  
Near Surface ◽  
The Pacific ◽  
Geostrophic Shear ◽  
Moored Current Meters ◽  
The Tropical Pacific

Abstract Near-surface shear in the Pacific cold tongue front at 2°N, 140°W was measured using a set of five moored current meters between 5 and 25 m for nine months during 2004–05. Mean near-surface currents were strongly westward and only weakly northward (∼3 cm s−1). Mean near-surface shear was primarily westward and, thus, oriented to the left of the southeasterly trades. When the southwestward geostrophic shear was subtracted from the observed shear, the residual ageostrophic currents relative to 25 m were northward and had an Ekman-like spiral, in qualitative agreement with an Ekman model modified for regions with a vertically uniform front. According to this “frontal Ekman” model, the ageostrophic Ekman spiral is forced by the portion of the wind stress that is not balanced by the surface geostrophic shear. Analysis of a composite tropical instability wave (TIW) confirms that ageostrophic shear is minimized when winds blow along the front, and strengthens when winds blow oblique to the front. Furthermore, the magnitude of the near-surface shear, both in the TIW and diurnal composites, was sensitive to near-surface stratification and mixing. A diurnal jet was observed that was on average 12 cm s−1 stronger at 5 m than at 25 m, even though daytime stratification was weak. The resulting Richardson number indicates that turbulent viscosity is larger at night than daytime and decreases with depth. A “generalized Ekman” model is also developed that assumes that viscosity becomes zero below a defined frictional layer. The generalized model reproduces many of the features of the observed mean shear and is valid both in frontal regions and at the equator.

scholarly journals On the Atlantic cold tongue mode and the role of the Pacific ENSO

2012 ◽  
Vol 9 (1) ◽  
pp. 163-185 ◽  
Author(s):  
R. A. F. De Almeida ◽  
P. Nobre
Keyword(s):  
Positive Feedback ◽  
Seasonal Development ◽  
Boreal Summer ◽  
Tropical Atlantic ◽  
Cold Tongue ◽  
Bjerknes Feedback ◽  
Western Basin ◽  
The Pacific ◽  
Atlantic Cold Tongue ◽  
Feedback Phase

Abstract. The dominant mode of coupled ocean-atmosphere variability in the Tropical Atlantic is analysed in this work from a melange of datasets, focusing on the seasonal development and evolution of the Bjerknes feedback responsible for the generation of the Atlantic cold tongue mode. The strength, seasonality and interannual variability of this mode is investigated through a joint EOF analysis of the anomalies of zonal wind velocity in the western basin together with sea surface temperature from the easternmost Tropical Atlantic, and analysed in conjunction with the depth of the 20 °C isotherm, representing the three mechanisms responsible for the generation of the Bjerknes feedback. Results from the EOF analyses confirm the robustness and seasonality of the Atlantic cold tongue mode, with a positive feedback phase peaking during boreal summer when the Bjerknes feedback is stronger. Analysis of an event in 2005 shows that the positive feedback is followed by a negative feedback phase triggered by the wind field and driven by oceanic heat advection. More importantly, we investigated the linearized impact of Niño events in the Pacific Ocean over the Atlantic by projecting the NINO 3.4 index over the Atlantic data. The Atlantic cold tongue mode has its variance reduced from 62% to 47% in the projected dataset, revealing that the Pacific ENSO has an inhibiting effect over its Atlantic counterpart.

The Philological Association of The Pacific Coast

PMLA ◽  
1935 ◽  
Vol 50 (4) ◽  
pp. 1373-1374
Keyword(s):  
Annual Meeting ◽  
Pacific Coast ◽  
Stanford University ◽  
The Pacific

The thirty-seventh annual meeting of the Philological Association of the Pacific Coast was held at Stanford University, California, on November 29 and 30, 1935.

A scanning electron microscopic study of the veliger larvae of the scallop argopecten purpuratus

1988 ◽  
Vol 46 ◽  
pp. 284-285
Author(s):  
G.C. Bellolio ◽  
K.S. Lohrmann ◽  
E.M. Dupré
Keyword(s):  
Morphological Description ◽  
Electron Microscopic ◽  
Larval Stages ◽  
Scanning Electron Microscopic Study ◽  
The Pacific ◽  
Argopecten Purpuratus ◽  
Veliger Larvae ◽  
20 Nm ◽  
Ethanol Series ◽  
Scanning Electron

Argopecten purpuratus is a scallop distributed in the Pacific coast of Chile and Peru. Although this species is mass cultured in both countries there is no morphological description available of the development of this bivalve except for few characterizations of some larval stages described for culture purposes. In this work veliger larvae (app. 140 pm length) were examined by the scanning electron microscope (SEM) in order to study some aspects of the organogenesis of this species.Veliger larvae were obtained from hatchery cultures, relaxed with a solution of MgCl2 and killed by slow addition of 21 glutaraldehyde (GA) in seawater (SW). They were fixed in 2% GA in calcium free artificial SW (pH 8.3), rinsed 3 times in calcium free SW, and dehydrated in a graded ethanol series. The larvae were critical point dried and mounted on double scotch tape (DST). To permit internal view, some valves were removed by slightly pressing and lifting the tip of a cactus spine wrapped with DST, The samples were coated with 20 nm gold and examined with a JEOL JSM T-300 operated at 15 KV.

Decolonisation and the Pacific

2016 ◽  
Author(s):  
Tracey Banivanua Mar
Keyword(s):  
The Pacific
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